The nicotinic acetylcholine receptor (AChR) is a pentameric integral membrane protein with the subunit composition alpha2beta gamma delta. The five subunits form an ion channel at their center whose opening and closing is controlled by the binding of acetylcholine. The nicotinic AChR in muscle is the best-studied of a large family of neurotransmitter receptors that include the receptor for GABA glycine and the neural AChR. Glutamate receptors are formed according to a similar pattern, but are more distantly related. Our laboratory studies the structure, function, and assembly of the nicotinic AChR in muscle. We investigate both the properties of the receptors in muscle cells and in heterologous cells in which the AChR is expressed after transfection of receptor subunit cDNA. Because of the similarity of members of the family, findings that relate to the AChR serve as a model for other receptors, which are targets for drugs that are relevant to the treatment of mental illness.